1. Field of the Invention
The present invention relates generally to systems for transferring particulate material and, more particularly, but not by way of limitation, to systems for transferring particulate material such as coal from an overhead storage container into railroad cars while maintaining the particulate material in a covered or protected condition.
2. Description of the Prior Art
One prior system for loading a tender car or hopper included a material distributing car rollingly supported on a trestle track, which was positioned above a railway track at a loading station. An example of a related system was disclosed in the U.S. Pat. No. 1,054,272, issued to C. C. Brackett. More particularly, as the hopper car was moved through the loading station, the distributing car was moved into overhead alignment with the hopper car. The distributing car was a "drop-bottom" type of hopper car and included a latching mechanism for preventing the inadvertent discharge of the retained material.
In some systems, unlatching devices were provided on the hopper car, or on the track supporting structures for opening the drop-bottom when positioned over the car to be loaded. Devices were utilized in some systems for returning the drop-bottom to the normally closed position after the material had been loaded. Various latching, unlatching and re-latching devices were disclosed in the U.S. Pat. Nos. 1,054,272, issued to C. C. Brackett; 1,084,481, issued to V. Ranier; 1,196,289, issued to W. H. & J. T. Rice; and 2,634,871, issued to R. A. Cline et al.
Other systems for the overhead discharging of particulate material into hopper cars were disclosed in the U.S. Pat. Nos. 2,238,200, issued to B. Willeke, and 3,374,908, issued to P. F. Giesking.
The Willeke patent disclosed a relatively long, horizontal overhead storage bunker utilized in charging lorries of coke ovens. In this particular system, the storage bunker had slotted openings at the bottom. The slotted openings were relatively small, and thus chunked coal retained in the bunker would not normally discharge through such slotted openings. A scraper plate assembly was connected to the upper portion of the coal hoppers and, as a lorry was moved on a track below the storage bunker, the scraper assemblies (disposed in the slotted openings) scraped the coal from the bunker and into the coal hopper.
In the Giesking patent, a relatively large storage container was positioned above a track at a loading station. A plurality of discharge outlets were formed at the bottom of the storage container. As a train of hopper cars moved through the loading station, each car was progressively loaded. Hatch covers were provided on each car to maintain the hoppers in a normally covered position. A hatch unlatching device was provided near the track at the loading station for successively placing each car in an open position to receive some of the material form the discharge outlets. A hatch closing and relatching mechanism was provided to return the hatch doors to the normally closed position after the loading operation had been completed. The loading was controlled by the engagement between a guide portion of the hopper car and a cam-like actuating device which was positioned at track side. The hopper car was supported on a wheeled truck by load absorbing springs. As a hopper car progressively was loaded, it settled upon the springs until the guide portion disengaged from the cam-like actuating device which was positioned at track side.
In the prior art systems, the material was not covered continuously during the loading operation. Thus, the particulate material was exposed to moisture or water (in the form of rain, snow, and the like) or blowing dust and debris, for example. This is particularly undesirable when the particulate material is in a dried or purified form.